It happens every day as soon as battery reaches 100%.
As @guystewart explained in the topic below, cause is incompatibility of chineese BMS with Victorn specifications. Instead of lowering CVL, BMS sets CCL to zero when battery is full. I tried to contact Basen Green (my battery brand) with questions about Victron compatibility (which they declare), but was silently ignored. Thus have to live with it.