Cap spec is 50 uF. Measured 40 uF. Which in the cap world is almost new.
I’d replace it. Mine was off by 5uF and wouldn’t start. Most of them are something like 5 or 10/35 , or 10/40, etc. I put a cap in that was 5uF larger than the OEM and it has worked fine for several years. Also, a lot of them are in the 5% tolerance range, so 5% of 50uF 2.5uF.
Cap specs and performance are about way more than just capacity. If it is electrically leaky, or is breaking down at higher volatges that will hurt performance. I’d replace the start cap if it were my AC unit.
In case you are dubious about my knowledge, I’ve been in the electronics troubleshooting and repair business for 30+ years (currently work at one of the top two medical device manufacturers in the world performing failure analysis and have been there for 22 of those years).