There seem to be two relevant Hebrew words used in both those passages of scripture. Consulting the book below, this is what I gleaned under the word SPOIL:
"5. To snatch away - natsal. Exodus 3:22 borrow,.. and ye shall
spoil the Egyptians. Exodus 12:26 lent unto them... and they spoiled
the Egyptians." (Analytical Concordance to the Bible, p 926, Robert
Young, 8th edition, based om the A.V.)
Interestingly, Young's own translation of the Bible renders those verses as:
[God speaking to Moses from ch.3 verse 21] 'And I have given the grace
of this people in the eyes of the Egyptians, and it hath come to pass,
when ye go, ye go not empty; and [every] woman hath asked from her
neighbour, and from her who is sojourning in her house, vessels of
silver. and vessels of gold. and garments, and ye have [put] them on
your sons and on your daughters, and have spoiled the Egyptians.'
[Moses writing the account of after the death of the first-born not
covered by blood on the lintels, Exodus 12:35-36] And the sons of
Israel have done according to the word of Moses, and they ask from the
Egyptians vessels of silver and vessels of gold, and garments; and
Jehovah hath given the grace of the people in the eyes of the
Egyptians, and they cause them to ask, and they spoil the Egyptians.
Bear in mind that this is dealing with the Hebrew word 'spoil', where it has the meaning of 'to snatch away'. We all know that there are lawful occasions for snatching away. It is lawful to snatch someone away from a spot where they would suddenly, and immediately, be killed. In that case, the snatching away saves a life. It is lawful. It is not stealing a soul as in kidnapping a soul. That would be a wicked thing to do. That's not what is going on here.
The second relevant Hebrew word is shaal, to lend, and it occurs in Exodus 12:36 which reads (in the A.V.) "...so that they lent unto them such things..." However, Young's own literal translation reads, "And Jehovah hath given the grace of the people in the eyes of the Egyptians, and they cause them to ask, and they spoil the Egyptians."
This is where Young's concordance shows the difference between lending, as in lending money or goods, which need to be repaid, and the meaning of the word used in Exodus 12:36.
"LEND, to - 1. To cause to join, lend, lavah, 5. Exodus 22:25 If
thou lend any money to any of my people... 6. To suffer to ask,
shaal 5. Exodus 12:36 [as quoted above].
This shade of difference in meaning is shown by two different words being used. The word for lending money or goods, that need to be repaid, is not the word used in the texts you ask about. The concordance shows that, when the Israelites asked, they were given those things, and that was because Jehovah God caused the Egyptians to look favourably upon the Israelites when they asked, so as to hand over what was asked for.
God had promised that they would exit Egypt with much spoil (i.e. lots of wealth and goods), and so they did, because they did what God told them to do, and asked for those material items. No way could that be construed as 'stealing'!
Nor does the account suggest they were 'fleeing', as your question puts it. They were told to leave, post haste, by Pharaoh! Read Exodus 12:30-33. He'd had enough of them and of Jehovah's plagues! He finally wanted rid of them, and not only gave them permission to leave, but urged them to leave, and allowed them to leave laden with goods his people had given to them.
To answer your question in summary - nobody stole anything from the Egyptians when the Israelites triumphantly took their leave, at Pharaoh's urging.