The past tense is formed by adding -ed to the end to form 'escalated'. This means the verb is regular.
"Have" is an irregular verb in English.
It's irregular.
regular or irregular
It's an irregular verb.
It's an irregular verb.
To swim is an irregular verb.
It's an irregular verb.
Ate is an irregular verb.
It's an irregular verb.
irregular
irregular
By is not a verb, so it is neither regular nor irregular.