As ReiX pointed out this is mainly due to eth increasing in value so the total USD locked would of course increase.
So to get the real figure we can track the rate at which eth is being locked compared to eth mined.
According to etherscan about 13k eth is mined per day.
According to defipulse we get:
30-Jun-19 1,688k eth locked
12-Feb-20 3,116k eth locked
Difference is 1,428k eth became locked
That is 227 days, which means an average 6.29k eth was locked per day, that is very nearly half (48%) the eth that mined per day is getting locked by defi.
So it's not a 20% increase in eth locked over the last 2 days, but it is very significant that in another 227 days you would expect basically all new eth mined to be immediately locked in defi.
There is probably a mechanism in defi to address this issue in case the price of eth skyrockets it will possibly start releasing eth since that amount of collateral isn't needed, athough this is very unclear since it would depend on which algo is being used. Maker probably has a different system for that than synthetix, for instance.