Honestly, tant dit que looks like a misspelling of tandis que.

Anonymous got it right.

Note that this error is very rare but there are a few occurrences elsewhere, for example in this forum.

Si on prend le végétarisme par exemple. Nous somme tous deux végétarien pour des raisons éthiques. Mais tant dit que moi, j’en aurais rien à foutre du jugement d’autrui (vous savez les jeunes : "T’es végétarien t’es sérieux ?!") mon frère aura tendance à masquer cette convictions devant les fan-boy du KFC et par contre le crier devant les membres de PETA. Tu vois ce que je veux dire.

It is interesting to note that DeepL finds the correct translation on the first try despite the wrong spelling while Google translates suggests the incorrect "as long as", sticking to tant and ignoring dit. DeepL result is probably due to a combination of several approaches. The first one must be based on a list of commonly misspelled words, but I rather suspect a second one where the software converts the word sequences into their phonetic equivalent and searches what words are most likely to be used at the given location.

There is also a very questionable expression in this sentence on nous enforce dans la gorge. Despite the English verb "to enforce" etymology, enforcer ceased to be part of the French vocabulary many centuries ago. Maybe that was a mixup of enfoncer and forcer or an anglicism, but DeepL got the idea again.