The problem with asking a questing about how to match string, and just providing two examples of the problem is that noone knows what you mean. Some simple "solutions" that match all your examples include:

/(2L)/
/(..)$/
/(\p{Nd}\p{LU})/
/(?:bar.|^)(..)/
(split /\./)[0]
/(?:.*\.)?(.*)/
/([^.]+)$/
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