@lucaannibale I turned 40 this summer and have been a long distance runner for a decade, started doing weightened bodyweight stuff early summer.
Every now and then i did something before but this time i stuck with it and noticed noticable gains on biceps, triceps, shoulders and upper back - and i'm probably pretty bad and weak.
I do kettlebell rows, band assisted chin ups (too weak for regular ones), resistance band pull downs, dead hangs, different push ups, kettlebell lat raises, weightened squats, step ups and bulgarian split squats.
And my diet is really bad atm, i do IF 16/8 but in my eating window there is lots of chocolate, cookies etc.
And i'm still seeing results.
I'm no way an expert but i'd guess you're doing too much with 5 days a week, eat more calories and throw in more protein sources and make sure ro rest and sleep properly.
I think it will work for you If it does for me.