You aren't necessarily actually sending it to a third party per se though. Less secure access also enables using software running on your own computer to access your email easily. For example offlineimap and imapfilter. In theory it ought to work with OAuth but damned if I can get it to work and any instructions a few years old are useless because something has changed in the interim.
It's actually less hassle to migrate off Gmail. Quite frankly there are few Google things that at this point aren't a hassle to work with. Google is poised to ruin adblocking in chrome with manifest v3, search is increasingly polluted by junk, gmail is now a pain to work with outside of a web browser and awful to use in a web browser, the play store is so bad as far as finding non junk non malware that its necessary to use an outside web page like say bing/duck duck go to find apps to install with play store which serves at best as an updater interface, workspace is a pain. Various actually useful services like reader picasa google+ are dead.
The only remaining useful end user services are youtube, maps, and android.
As someone who used to be excited about Google stuff its kind of disappointing.
Gmail user from June 2004-2022 but soon no longer. Thanks for 18 years of good service for the absolutely ridiculously low price of I think $80 to date.