Two layers of cheep heatshrink should cope ok with 230 volts.
or wrap a few turns of GOOD electrical tape (NITTO?) around the spade connector and then a layer of cheep heatshrink on top
My current quick fix 'good enough' fav is that overpriced SOS silicone ---stretch--- 'repair' tape which seals itself to itself nicely.
If I want the job to not get done again for a LONG TIME, then I add one layer of quality heatshrink on top of that.
That combo is good for lots of volts, current, temperature and joint rigidity
It's not cheap and you only get a tiny roll of the stuff that does not go as far as a roll of electricians tape.
Some brands may be half assed knockoffs, so far the best I've tried has been the 'SOS' badged one
FWIW, I'm not plugging SOS, unless the company wants to throw some benefits my way to finance a "666 uses for..." vid on Youtube
and a battlers royalty percentage
EDIT: Whatever you do ensure that the spade connectors are crimped properly and tensioned properly on the terminals for a tight fit
If they are physically loose or wonky when tested, heatshrink won't help much, except contain the sizzle for a while...