Out of memory - System::TMonitor::QueueWaiter

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.15.2

Error message:
Out of memory

Stack trace:
(00417DC_) System::TMonitor::QueueWaiter
(00417DC_) System::TMonitor::QueueWaiter
(003A29D7) System::Classes::TComponent::FreeNotification
(0023838C) Vcl::Forms::TCustomForm::CMShowingChanged
(00861F28) C2103_0
(00278F45) Vcl::Controls::TWinControl::CreateHandle
(0023340C) Vcl::Forms::TCustomForm::ReadState

The problem happens rarely. I cannot reproduce it.