Difference between 5.12.2 and 5.14.1 if you set PERLIO_DEBUG=

$ perl  -le " open my $fh => '<:raw', \'blah' "
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-e:1 scalar => 0x12113000
-e:1 raw => 0x68b5c6c0
-e:1 Layer 1 is raw
-e:1 openn(raw,':raw','r',-1,0,0,0,1,0x3f5230)
-e:1 Layer 0 is unix
-e:0 Destruct 0x3f3f7c
...
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-e:1 scalar => 64fc3000
-e:1 raw => 66c53840
-e:1 Layer 1 is raw
-e:1 openn(raw,':raw','r',-1,0,0,00000000,1,003f5230)
-e:1 Layer 0 is unix
-e:1 Layer 0 is scalar
-e:1 PerlIO_push f=009941dc scalar r 0099a904
-e:1 PerlIO_push f=009941dc raw r 003f47a8
-e:1 :raw f=009941dc :scalar
-e:0 PerlIO_pop f=009941dc scalar
-e:0 Destruct 003f4004
...
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On the other hand, if you use

$ perl  -le " open my $fh => '<:encoding(UTF-8)', \'blah' "
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-e:1 encoding => 0x1076000
-e:1 Layer 1 is encoding
-e:1 openn(encoding,':encoding(UTF-8)','r',-1,0,0,0,1,0x3f5208)
-e:1 Layer 0 is unix
-e:1 Layer 0 is scalar
-e:1 PerlIO_push f=0x9b4024 scalar r 0x9ba20c
-e:1 PerlIO_push f=0x9b4024 encoding r 0x9b9c4c
-e:0 PerlIO_pop f=0x9b4024 encoding
-e:0 PerlIO_pop f=0x9b4024 scalar
-e:0 Destruct 0x3f3f5c
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