Your integration update introduced a new variable (companyId), and you use it in your updated ACS URL. The ACS URL changed from https://login.myapp.io to https://login.myapp.io?connection={org.companyId}. In this case, ensure that the dynamic ACS URL is also valid for existing instances where the companyId value isn't set.
To handle empty companyId values, you can define the ACS URL as:
https://${empty org.companyId ? 'login.myapp.io' : 'login.myapp.io?connection=' += org.companyId}This expression handles both scenarios where companyId is populated or empty. See Dynamic properties with Okta Expression Language.