I'm sorry, I can't seem to find who posted about this company on the BRK board right now.
But I did a little digging, see below:

Protector Forsikring ASA, ticker PROT.OL (Norway property and casualty insurance)

Since 2005-05-25 using Yahoo data:

Annualized Return 0.246700
Annualized Std Dev 0.409100
Annualized Sharpe (Rf=0%) 0.603100
maxDrawdown 0.793421

Top five drawdowns using Yahoo data:

From Trough To Depth Length To Trough Recovery
1 2007-05-30 2008-10-31 2011-01-31 -0.7934 926 363 563
2 2018-01-11 2020-03-19 2021-04-15 -0.7824 814 547 267
3 2011-05-16 2011-10-13 2013-01-18 -0.2982 425 106 319
4 2014-07-24 2014-12-16 2015-01-28 -0.2613 130 104 26
5 2016-10-26 2017-03-31 2017-10-09 -0.2433 242 112 130

Summary of rolling one year returns using Yahoo data:

Min. :-0.71455
1st Qu.: 0.01166
Median : 0.35054
Mean : 0.38618
3rd Qu.: 0.64165
Max. : 3.17453

CONCLUSION:
Massive hits in 2008/2009 and 2020 according to Yahoo data, but great returns otherwise.

2020 Annual Report:
protectorforsikring.no: PDF document
If there was an explanation of their share price decline, I missed it.
On page 10 is a graph of share price, showing a drop from about 55 to 20 in the 2020 period, which isn't quite the -78% drawdown in the stats above but maybe there were some currency effects at play (data was from Yahoo). Still a massive drawdown, and I didn't see a reference to it in the AR, but might have missed it.

The website I have for annual reports only goes back to 2013, so no 2008 or 2009, but for the other reports here's the site I used for ARs
protectorforsikring.no - Annual reports

A Yahoo data glitch? But I can't seem to pull it up in alphavantage.
FWIW, this site seems to corroborate massive share price hits:
companiesmarketcap.com - Stock price history

Here's some more info
simplywall.st - Do protector forsikrings obprot earnings warrant your attent

Maybe the OP has some insight?