One mistake at work that you’ll never make again?

Never mistaking work friendships as genuine friendships ever again!

Not calling out delays and mistakes of fellow employees. I’ve been a good person to work with throughout my career and it has helped me grow quick. I’ve been patient with colleagues who take time to complete a task or either struggle with work. Mainly with the intention to not put more pressure on them. But this doesn’t work well in companies where there’s cut throat competition. This has backfired couple of times, where I was considered as someone not serious and proactive enough to call out blockers.
So try to gauge the culture and power distance in your company and fine tune your empathy with fellow colleagues accordingly.

Working for impact and value instead of working for a promotion 🤦‍♂️

Taking responsibility to fix something during an escalation/emergency. A lot of workers in India are Umarells (Unkils standing on side of road giving instructions to workers but not working), and would then seek you out for their own work to do their jobs citing false emergencies.
If it is broken, and you are not the one to fix it, don't do it. You'll be then in the firing line when it goes bad again.

Hit on a girl