Sales tax and Vat issue within memberships - membership fee increases incorrectly when the membership has an error

When sales tax is enabled (as per https://docs.civicrm.org/user/en/latest/contributions/sales-tax-and-vat/) there is an issue.

• Tax and invoicing is enabled
• A sales tax financial account type has been created
• This new financial account type has been assigned to the Member Dues financial type (so all memberships have the sales tax applied).

If you then add a new membership via the CRM member menu. Then assign it to a contact, choose a membership type (which has a fee) and create an error deliberately (e.g. choose a membership end date before the start date). The membership fee will then change upwards automatically to an incorrect amount. And if you try to save the membership again with a deliberate error the membership price increases again. An again etc.

This has been recreated on the CiviCRM sandbox demo and I've attached a screenshot of a $100 membership price increasing.