If you'll only be overseas temporarily on holiday or for a work trip, just contact Migri and let them know the dates you'll be abroad. Otherwise you run the risk of receiving a negative decision if you aren't in the country on the date they make the decision.
A friend of mine recently received her Finnish citizenship and simple notified Migri for the period she was going to be abroad and they ensure that they put her application on hold for that period and only made and delivered the decision once she was back in Finland.
Regarding the cancellation of EU permanent residence:
"Changes in the grounds for a residence permit
Your residence permit may be cancelled if the grounds on which it was granted no longer exist. This may for example happen if your residence permit was granted for working in Finland but your employment relationship has ended.
Your EU residence permit will be cancelled if you have lived outside the European Union for a continuous period of two years, or outside Finland for a continuous period of six years."
For more info see:
https://migri.fi/en/cancellation-of-a-permit