Why is the quantity in stock -1?

Question

WooCommerce

Hello! There is a clothing store, sizes are made by attributes, variations are created from attributes. All variations are set

to "Manage inventory"
"Do not allow pre-orders"

When an item runs out of stock, it's zero in stock, but sometimes -1 appears. Rarely, everything looks like everywhere else, I can’t understand the patterns and reasons.
Which way to look?

Answer 1

Write-off and recovery of balances, in addition to the standard wc_stock_function.php, can also be set through the payment gateway.
Look in the code for wc_reduce_stock_levels to see which plugins do this.

Answer 2

https://oracle-patches.com/db/mysql/3814-tranzakts...
https://webistore.ru/sql/transakcii-v-mysql/