Was the TM drop rate increased?

Probably luck, haven't gotten a single one myself.

I've noticed an increased spawn too. I normally get a charged TM from solo raids once a month if I'm lucky, I've gotten like 4 since the event started.

Not my experience. Still a great shortage of cTMs after Larvitar CD and rarely get them. Especially when I needed 7 for my last Machamp and have used 5 so far for my last SD Tyra.

^ why TSR analyses such big numbers in aggregate. Even if you're doing a hundred raids, you're looking at such a small part of the sequence as to not produce statistically valid results.