How do you know 'google takes election stuff seriously'? Causation!=effect. TBH I'm surprised the OP even asked the question 'why did an algorithm remove my stuff?'. No google employee is going to tell you (even if they knew, which is quite doubtful given the complexities of machine learning). If you sign up for a service which is machine-managed, you are subject to the whims of the machine. Occams razor suggests it is unlikely there is a conspiracy, or malice at play. The machine is just doing its job for its masters, possibly badly, possibly not, but the general populace will never know one way or the other.
I can provide another datapoint. When I was at Arist (YC S20) we experienced tons of content filtering at the carrier level around election time. Messages that merely mentioned the word "vote" or "election" were getting blocked by many carriers. A few months later none of these restrictions seemed to exist. So not just Google.
Oh yeah carriers regularly filter based on content. I've posted about it extensively on HN before. I only have line-of-sight into them doing this for SMS messages arriving from businesses i.e. via Twilio, Telgorithm, Bandwidth, etc. I don't know one way or the other whether they also do this for regular SMS messages but I imagine automated 10DLC are under more scrutiny than a regular SMS user.
The filtering is phrase and word based generally, but sometimes also seems to use an ML model. We were able to use our own ML analysis to figure out the exact words causing content blocking and which carriers in a lot of scenarios. But yeah, it's definitely a thing at every major carrier.
what did your voting tool do? I suspect google like many other tech companies are trying to avoid having their platforms used to manipulate election activities and the definition of manipulate might be very broad. It being funded by a campaign might not matter to google at all.
Being funded by a campaign might even be a negative, as it would likely increase the odds that the address is being used for election manipulation.
It would be easy to register <state>voting@gmail.com, start using it as a contact for public-facing election-oriented documents, and get at least some people confused about whether I was officially associated with <state>'s election apparatus. Given the current environment, I'm positive Google very much doesn't want their systems being used to (even accidentally) impersonate election officials.
I made a voting tool (legitimate and funded by a campaign) with a throw away email as the contact:
<state><voting>@gmail.com
It was removed. For the OP, this could be an auto flag error or this could be something else.
(Edit: I bet) Google takes the election stuff seriously.