I feel like the term self-insert is hard to define. If self-inserting just means inserting aspects of your real life and personality into your writing, then that's how everyone writes. Like, if you're a chemistry student in college, it makes sense that you'd be inclined to write about a character who's a chemist or something. It's familiar and you have more knowledge of the subject than if you wrote about an architect.
Some of the most iconic characters in fiction are in some ways self-inserts or inserts of the people the author knows in life, such as almost all the characters in To Kill a Mockingbird, Guts and the Band of the Hawk from Berserk who were inspired by Miura (rest in power) and his old friend group, etc. etc.
The most important thing about writing self-inserts is making sure the characters are also interesting people or otherwise well-written characters. With that in mind, self-insert all you want. If your writing's good, then your audience won't notice or care.