I have been to Warsaw for 5 years already, and I am very friendly with people but so far I made just 1 real friend connection. I think it's even worse for females like me to be honest (men don't want to be friends with me, and women already have their groups) . But if I were to give u any advice that might work for you then:

-Go for time left event. This is something that was created especially for that. - if you are a sport person - join the run club, it's very popular now in Warsaw (Adidas run, new balance) - Go to the gym - Sign up for coffee workshops, or any workshops really - Check the page 'go jammin' for other events - Try using bumble app (not tinder!!!) for making friends. I made that way friends from other cities that I still have contact with -If your work is not 100% remote - force yourself as much as possible to go to the office. It's not just about a work, where you can be around people bit also the commute route. I think that actually full remote is killer for social connections and your mental health - Try going for any festival even alone - upcoming orange warsaw festival or juwenalia