why did svb fail and not other banks? most of its customers are tech companies, so?

this post is not necessarily about stock market.

i am trying to understand why only svb failed and other banks did not.

i know svb in primarily invested in tech industry and many tech companies are laying off its employees.

but why did this cause svb to fail? why did only this bank fail and not other banks? did the companies who loaned money from this bank failed to pay back?

did it do any illegal stuff or did not follow regulations?

all the news i am reading about it is just saying it failed because it is preferred banker for tech companies. so what?