[headcanon]

First off, "Senior" is a pretty nebulous term and can mean different things to different people and different companies. Some companies have fairly detailed definitions of what is expected at different levels, and others don't. For the latter, "Senior" likely means "we don't want to have to teach you to code". Whether or not you want to work at a place like that is up to you and the conversation that you have with them in the interview. I wouldn't worry too much about labels, especially in times like these.

It seems like you've got a bit of imposter syndrome. Its normal. You've got four years of experience at multiple companies. I'm sure it will be challenging but its better to push yourself a bit and fail sometimes than stagnate forever. You'll do just fine.