I’ve tried looking it up and it seems like it’s capped at 2 weeks but I cannot find a definite source

I’ve also seen it’s more a size thing than a time thing (2nd source) as mempool capped at 300mb

https://bitcoin.stackexchange.com/questions/96363/what-happens-to-transactions-in-the-mempool-when-their-parent-transaction-expire

https://coingate.com/blog/post/btc-mempool-stuck