Worked with my company for years, usually pretty happy there. Person that I line manage been there a few years. Nice enough person but there's been issues before.
It's a busy company but quite relaxed in outlook with a "no blame" culture, which is either good or frustrating depending on what's happening. I have suffered from anxiety in some other jobs but am usually ok here because I know I won't get torn a new one if something has gone wrong etc. Luckily I know the ropes well and don't often forget stuff or mess up.
Anyway it's gone from busy but manageable to usually always super busy with me often hitting a wall and having little time to think before getting things done, juggling lots of stuff at once. Changes have been made recently to accommodate things and try to smooth it over but I'm not sure that it's working. I've been doing as best as I can however my assistant frequently forgets to do things, or makes mistakes and I'm constantly picking up after them, usually when they're on holiday or off sick and I have a team member telling me that X urgent thing was supposed to be done a month ago and my assistant hasn't done it. There's even been occasions when they've told me it's been done and then later on I find out it's not and have to rectify it. I'm about at the end of my tether because there's only so many times you can say please do X today or ask if they've finished this thing and been told yes, when you later find out it's sitting untouched. And this isn't just a recent thing.
Anyway that's bad enough and I am already going to speak to my own boss (who is pretty high up) about things to discuss a way forward but then another team member phoned me to discuss the issues as it's not just me who it's affecting and told me something very concerning. Basically that someone else (wouldn't tell me who) had spoken to them and mentioned that my assistant had, at one point, apparently been doing work for someone else when they were supposed to be working for us. During company hours in other words, which I believe is fraudulent. We were all wfh at this point. Not sure how the person knew about this supposed other job but I was told it is someone that my assistant is quite friendly with so perhaps they were seen somewhere, not sure. This seemingly coincided with a period where they had left lots of work undone for months, and I'd only found out about it after a long period had passed. When gently questioned they'd said that there had been some kind of "issues" at home etc, but unspecified (couldn't really say what exactly had caused it) that had meant that they'd dropped the ball and forgotten to do all this work. And now I'm being told that they were moonlighting at work.
I have no proof of this of course and it's very much a he said she said situation. But should I mention this rumour to my boss when I voice my other concerns? I'm not sure what, if anything I should say given that it's just something another staff member told me but it would certainly explain a lot! And also what if something was to come to light later on and I'd said nothing?
Thanks for any advice.