For Finland 3 months is bit special, mine is 1 month and previous job was 2 weeks(up to 5 years). From employer side legal minimums are: under 1 year 2 weeks, under 5 years 1 month, under 8 years 2 months, under 8 years 4 months and over 12 years 6 months.

Penalty from employee side seems to be monthly wage, so in this case 3 month salary. Ofc, seeing how company is probably doing I wouldn't be too worried of them coming after him...