Yes, its the "protest vote" element of LibDem support that literally fell off a cliff post 2010 (in at least some places, it transferred pretty much wholesale to UKIP in the 2015 GE) and its the part that isn't likely to meaningfully return any time soon, the odd flurry in local by-elections notwithstanding.
Though—given the thread title—it should be mentioned that there is a difference between such protest voters (the I-hate-them-alls, who then generally voted UKIP in 2015) and the anti-Labour 2010 Lib Dem/2015 UKIP/2017 Conservative voter as found in Bishop Auckland. Whose consolidation behind the Conservatives will no doubt be the source of much stupid #realignment analysis for years to come.