Auditor competency

First, it is your organization that has the authority to establish competency requirements for internal auditors. Second, your organization should, as a good practice, update those requirements. Normally, updating includes knowing ISO 9001:2015 and knowing good auditing practices, perhaps considering an update for ISO 19011:2018.
So, if you updated your ISO 9001 training to the 2015 version and you answer to all internal requirements for internal auditors there would be no problem.

The following material will provide you with information about internal audits:
- ISO 9001 – Five Main Steps in ISO 9001 Internal Audit
https://advisera.com/9001academy/knowledgebase/five-main-steps-in-iso-9001-internal-audit/
- free online training ISO 9001:2015 Internal Auditor Course
– https://advisera.com/training/iso-9001-internal-auditor-course//
- book - ISO Internal Audit: A Plain English Guide
https://advisera.com/books/iso-internal-audit-plain-english-guide/