I hear this claim a lot (that Gmail's spam filter is so much better than others) but that hasn't been my experience. Spam was not a problem for my corporate email account at my last job that used Exchange and after switching from Gmail to Proton Mail last year (with the same email address on my own domain) I haven't noticed any real difference in the amount of spam than makes it to my inbox.

It may have been true that Gmail did a much better job than most other services when it first launched but I don't think it's been true for several years now.