I am also google customer moved over to squarespace and have a tonne of new entries and all the malign ones mentioned.
I've just got mailerlite and tried to authenticate but it says "SenderIP/SPF has more than one record, remove all others and leave only one.
so i have 2 x TXT SPF entries that have 'goodle' in them
and then 1 TXT SPF that is mailgun.
Q: can i delete these? what might go wrong?
Q: can i use mailerlite if they have already attached malign to my domain????