The problem should be either in a regular expression statement or in the code before before that statement where the hash %findReplaceH is handled and modified for use in that regex statement

As others have put - it is hard to tell where the spaces are coming from without more code. However, your replacement hash looks fine, so you probably have a sneaky space in your replacement code along the lines of (but a '#' instead of ' '):

my $string = '<TList.Bullet><TList.Item>sometext</TList.Item></TList.B
+ullet>';
print "Before : \'$string\'\n";

my %find_replace = (
        q[<TList.Bullet>]     => q[<ul>],
        q[</TList.Bullet>]     => q[</ul>],
        q[<TList.Item>]     => q[<li>],
        q[</TList.Item>]     => q[</li>],
);

for (keys %find_replace){
    $string =~ s/\Q$_\E/\#$find_replace{$_}/;
}

print "After : \'$string\'\n";

## Gives :
# Before : '<TList.Bullet><TList.Item>sometext</TList.Item></TList.Bul
+let>'
# After : '#<ul>#<li>sometext#</li>#</ul>'
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But it woul help to see the replacement code and come real input / output.

Update : Forgot to include output... Now included with code.

Thanks for the suggestions, I've inserted my code below. Please let me know if you see the code that is generating the blank space.

use strict;
use File::Find;
use File::Path;
use File::Copy;
my $folderPath = "C:/Folder1";

my %findReplaceH = (
q[<TList.Bullet>]=>q[<ul>],
q[</TList.Bullet>]=>q[</ul>],
<TList.Item>]=>q[<li>],
q[</TList.Item>]=>q[</li>],
my $useRegexQ = 0;
$folderPath =~ s[/$][];

$folderPath =~ m[/(\w+)$];
my $previousDir = $`;
my $lastDir = $1;

my $totalFileChangedCount = 0;
sub fileFilterQ ($) {
my $fileName = $_[0];

 if ($fileName =~ m{\.xml$}) {
print "processing: $fileName\n";
return 1;};

return 0;
};

sub processFile {
 my $currentFile = $File::Find::name; # full path spect
my $currentDir = $File::Find::dir;
my $currentFileName = $_;

if (not fileFilterQ($currentFile)) {
  return 1;
}
if (not(open FILE, "<$currentFile")) {die("Error opening file:
$!");};
 my $wholeFileString;
  {local $/ = undef; $wholeFileString = <FILE>;};
  if (not(close(FILE))) {die("Error closing file: $!");};

# do the replacement.
 my $replaceCount = 0;

 foreach my $key1 (keys %findReplaceH) {
    my $pattern = ($useRegexQ ? $key1 : quotemeta($key1));
  $replaceCount = $replaceCount + ($wholeFileString =~
s/$pattern/$findReplaceH{$key1}/g);
 };

if ($replaceCount > 0) { # replacement has happened
$totalFileChangedCount++;
# get the file mode.
my ($mode, $uid, $gid) = (stat($currentFile))[2,4,5];

  # write out a new file.


 if (not(open OUTFILE, ">$currentFile")) {die("Error 
opening file: $!");};
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 print OUTFILE $wholeFileString;
if (not(close(OUTFILE))) {die("Error closing file: $!");};

 # set the file mode.
 chmod($mode, $currentFile);
chown($uid, $gid, $currentFile);

 print "$replaceCount replacements made at\n";
  print "$currentFile\n";
}
};

I'm not sure if you have a 'cut and paste' issue, but the code you supply has syntax errors. The hash declaration for %findReplaceH is not terminated with a ), and you have a q[ missing on one line. I get:

"my" variable $folderPath masks earlier declaration in same scope at C
+:\gash.pl
line 17.
"my" variable $folderPath masks earlier declaration in same scope at C
+:\gash.pl
line 19.
Unmatched right square bracket at C:\gash.pl line 14, at end of line
syntax error at C:\gash.pl line 14, near "<TList.Item>]"
syntax error at C:\gash.pl line 68, near "print"
Execution of C:\gash.pl aborted due to compilation errors.
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I added use warnings;

Update 2
Fixing these issues, I then found that neither subroutine is actually called, I guess you are missing a File::Find.
Anyway, so I extracted the RE and and tried a simple test. This time I assumed that the data had embedded spaces, so I altered the RE:

my %findReplaceH = (
    q[<TList.Bullet>\\s*] =>q[<ul>],
    q[\\s*</TList.Bullet>]=>q[</ul>],
    q[<TList.Item>\\s*]   =>q[<li>],
    q[\\s*</TList.Item>]=>q[</li>],
    );

my $useRegexQ = 1;

my $wholeFileString='<TList.Bullet><TList.Item> sometext </TList.Item>
+</TList.Bullet>';
my $replaceCount = 0;
    
foreach my $key1 (keys %findReplaceH) {

    my $pattern = ($useRegexQ ? $key1 : quotemeta($key1));
            
    $replaceCount = $replaceCount + ($wholeFileString =~ 
                        s/$pattern/$findReplaceH{$key1}/g);
};
print "$wholeFileString\n";
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and it appears to work correctly without extra spaces:

<ul><li>sometext</li></ul>
[download]

Note that I set $useRegexQ to force quotemeta

FYI, all spaces are blank :D