One of the important points what Scripture warns us at end time is:
This will be the time when the attack on the word of God is allowed.

We can see it in the parables of the Bible:

“Matthew 13: 36 Then Jesus sent the multitude away, and went into the house: and his disciples came unto him, saying, Declare unto us the parable of the tares of the field.
37 He answered and said unto them, He that soweth the good seed is the Son of man;
38 The field is the world; the good seed are the children of the kingdom; but the tares are the children of the wicked one;
39 The enemy that sowed them is the devil; the harvest is the end of the world; and the reapers are the angels.
40 As therefore the tares are gathered and burned in the fire; so shall it be in the end of this world.
41 The Son of man shall send forth his angels, and they shall gather out of his kingdom all things that offend, and them which do iniquity; {things…: or, scandals}
42 And shall cast them into a furnace of fire: there shall be wailing and gnashing of teeth.
43 Then shall the righteous shine forth as the sun in the kingdom of their Father. Who hath ears to hear, let him hear.”

Here, there written wheat and tares sprang up in the church.
Good wheat and tares are both related to bread, word of God.

Devil sowed tares, and evil Christians grow in the church.
Tares relate to word of God, doctrine. So, what this scripture warns us is:
Evil teaching believing Christians will spread within the church.

Matthew 13: 33 Another parable spake he unto them; The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till the whole was leavened. “

In this parable, leaven means the sin to be spread as per below scripture:

Matthew 16:6 Then Jesus said unto them, Take heed and beware of the leaven of the Pharisees and of the Sadducees.”

So, within the above parable, leaven, which a woman took, is the sin to be spread.
And “leaven, which a woman took, and hid in three measures of meal, till the whole was leavened” means sin will gradually spread till it spread all of the church. So, what this parable warns is: spreading of false or sin teaching within the church till the end of the world.

Matthew 24: 7 For nation shall rise against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes, in diverse places.”

This is the prophecy at the end of the world. It is here written about famines.
Famine means a lack of bread, wheat. This is the parable about the time when the lack of eatable sermons are to occur in the church.

Revelation 6: 6 And I heard a voice in the midst of the four beasts say, A measure of wheat for a penny(denarius), and three measures of barley for a penny(denarius); and see thou hurt not the oil and the wine. “

Here, there described that: “A measure of wheat for a penny(denarius), and three measures of barley for a penny(denarius)”

A denarius is the money of a one-day labor fee. So, this means wheat and barley will become a costly one.
Wheat and barley relate to bread, word of God. So, it means
word of God, good preaching becomes costly and difficult to get at the end time.

Revelation 6: 8 And I looked, and behold, a pale horse; and he who sat on it had the name Death, and Hades was following with him. And authority was given to them over a fourth of the earth, to kill with sword and with famine and with 2pestilence and by the wild beasts of the earth.”

There also written about famine. Famine means the lack of bread, the lack of word of God, and its healthy doctrine. So, as a conclusion, Scripture clearly warns us of the corruption of teaching and spreading of false doctrine will happen in the end-time church.