No because that doesnt make sense and the xp debt would never be used.
If the player is 10 xp into their level and they lose 20%, they only lose 2xp. If they have 1xp into level, then they won't lose any xp.
Setting "Use the players xp (not the level xp) to calculate loss" to false will calculate the xp loss based on the chunk of the level.
If level 70 > 71 requires 28,776 xp, then regardless of how far into that level the player is, the calculation will be done based on that xp amount.
Example:
IF they are 10,000 xp into the level, and the xp loss mod is set to 20.0, they will lose 5,775.2 xp.
IF they are 1,000 xp into the level, and the xp loss mod is set to 20.0, they will still lose 5,775.2 xp, 4,775.2 of which will be accumulated as xp debt if that is enabled. Otherwise it will simply set their current xp value to 1.
Setting true for "Use the players xp (not the level xp) to calculate loss" is meant to base it on the total accumulation of xp that the player has (in the case of level 70, they would have around 1,010,365 xp) and is only recommended for more difficult servers, with a lower loss value.