I once again don't have a good solution for 'how do I email a large file' but https://webwormhole.io/ is useful and simple, particularly for sending something big to someone you're video chatting with.
Do we trust them and their security approach? Genuine question - it was a major selling point to me that Mozilla were operating Firefox Send. I was happy to give some trust to them and their approach to encryption.
Keep in mind that if security is important, you can still self host Send.
That said, the thing that apparently killed Mozilla Send (becoming a hub for spam and child abuse material) was much easier to handle. The last big project I was involved in was an automated photoDNA scanner to detect suspected child abuse material. It would pull in various lists of hashes of known bad material and flag any matches for manual verification by the department of the Dutch police that handles such things.
Once you have built a secure and easy to use way to transfer large files to multiple people you have built a piracy enabling tool and you're eventually going to be sued by various media cartels for trillions of dollars and your tool will be blocked by network operators who also don't want to be sued.